Body Diffusion-Weighted MR Imaging Using High b-Value for Malignant Tumor Screening: Usefulness and Necessity of Referring to T2-Weighted Images and Creating Fusion Images

Abstract

To evaluate the potential usefulness of high b-value body diffusion-weighted images (DWIs) as a screening tool in the depiction of abdominal malignant tumors. We selected 110 abdominal magnetic resonance examinations (1.5 T; 60 men; age range, 25-90 years) with and without malignant tumors (n = 37 and n = 73, respectively). Axial DWIs were obtained by single-shot spin-echo (SE) type echo planar imaging (EPI) sequence with inversion pulse (repetition time, 6,800 msec; echo time, 100 msec; T1, 150 msec; b value, 1,000 sec/mm(2)) without breath-holding. Two radiologists independently interpreted the DWIs, T2-weighted images (T2-WI), all three types of images including DWIs, T2-WIs, and fusion images at the same time (DWIs + T2-WIs + fusion) with 7-14 days' interval, and the diagnostic confidence for each patient was scored. The area under the curve (AUC) of the composite receiver operating characteristic (ROC) curve of DWIs + T2-WIs + fusion (0.904) was significantly higher than those of DWIs (0.720; P < .001) and T2-WIs (0.822; P < .05). Both sensitivity and specificity were higher in DWIs + T2-WIs + fusion (89.5% and 81.9%, respectively) compared with those of DWIs (72.4% and 59.0%; P < .01 and P < .001, respectively). Abdominal high b-value DWIs have a high sensitivity and specificity for malignant tumors when T2-WIs are referred and image fusion technique is employed, suggesting that it may potentially be a new screening tool.